1. Field of the Invention
The present invention relates to a sheet stacking apparatus incorporated in, e.g., an automatic teller machine of a financial agency such as a bank and used to stack banknotes and the like.
2. Description of the Related Art
In an apparatus of, e.g., an automatic teller machine which receives sheets, e.g., banknotes one by one and stores them in the stacking state, the depth of the sheet stacking section serves as a factor to largely influence the performance of the apparatus.
More specifically, if the stacking section is excessively shallow, the trailing end of a sheet previously received and the leading end of a sheet to be received next collide; if the stacking section is excessively deep, the sheets are not set horizontally but rise to cause erroneous stacking.
Conventional stacking apparatuses of this type can be divided into a fixed depth-type stacking apparatus in which the stacking bottom surface of the sheet stacking section is fixed and a variable depth-type stacking apparatus in which the stacking bottom surface is controlled to move downward in accordance with the number of sheets that are to be received and stacked.
In such a conventional stacking apparatus in which the depth of the sheet stacking section is fixed, however, the stacking depth capable of appropriate stacking sheets is limited, and thus the number of sheets to be stacked is small.
Furthermore, in order to handle a maximum number of sheets by using the fixed depth-type apparatus, a cumbersome operation of temporarily storing a predetermined number of sheets at some place and transferring them to another stacking place, and receiving the remaining sheets must be repeated. This operation complicates the apparatus and degrades the handling efficiency.
On the other hand, a variable depth-type apparatus can handle a large number of sheets if the quality of the sheets is the same and comparatively good. However, assume that the quality of the sheets is poor, i.e., used sheets are to be handled. Since used sheets have various thicknesses, as the number of stacked sheets is increased, the stacked sheet height varies even if the number of stacked sheets is the same as the good-quality sheets. The height of the poor-quality stacked sheets can reach to about five times that of the good-quality stacked sheets. Since the conventional apparatuses cannot cope with a change in stacking depth caused by the different sheet qualities, they cannot maintain the optimum sheet stacking depth, and their performance varies. In particular, in a spring-type sheet stacking apparatus, since the operation varies, the stacking depth is not changed with a small weight change.
This fact will be described in more detail.
FIGS. 1 and 2 show an arrangement of a banknote stacking means of a conventional banknote stacking apparatus. The operation of a shutter 204 is controlled in accordance with the number of banknotes A stacked on it. As described above, if the banknotes have a poor quality, they cannot be sufficiently pushed by a striker wheel 203 even at a stacking depth that might have been appropriate for good-quality banknotes, as shown in FIG. 1. In this case, the banknotes A rise to interfere with insertion of a following banknote A, thus causing jamming.
Inversely, with new banknotes, if the stacking depth is excessively large, as shown in FIG. 2, the banknotes rise to cause jamming.
In this manner, the conventional banknote stacking means cannot sufficiently cope with a difference in stacking height due to the quality of the banknote, and continuous banknote stacking cannot be stably performed.
Hence, a method as shown in FIG. 3 is employed. According to this method, when a certain number (relatively small) of banknotes, e.g., about 100 banknotes A are stacked on the shutter 204, loading of the banknotes is temporarily stopped. A pusher 207 is moved downward to a position below the support positions of upper press plates 205 to push the banknotes A stacked on the shutter 204, and thereafter the pusher 207 is moved upward to the home position. After these series of storing operations, loading of the banknotes A is resumed. With this method, however, the handling time is prolonged very much.
In addition, with the conventional banknote stacking means, has no effective apparatus for performing a continuous stacking operation in which, while the banknotes are loaded in a stacking safe from above, the stacked banknotes are unloaded from below the stacking safe.